Pickup Ions in the Mass Interval 20-30 amu Observed with SOHO/CELIAS/CTOF vs. Model Calculations of Distribution Functions Accounting for Heliospheric and Interstellar Seed Populations

A.T. Bogdanov, B. Klecker, D. Hovestadt, H. Grünwaldt, M. Hilchenbach, E. Möbius, F. M. Ipavich, F. Gliem, P. Bochsler

Paper presented at AGU Fall Meeting, 8-12 December 1997, San Fransico, CA, USA

Newly obtained results are presented on neon and possibly magnesium pickup ions from the SOHO/CELIAS/CTOF Instrument - a time-of-flight mass spectrometer which measures the charge composition of ions from solar wind energies up to 35 keV/e. Due to its large geometrical factor and the continuous observation mode, for the first time singly charged Ne ions originating from the neutral interstellar gas component could be measured as deep in the heliosphere as one astronomical unit to the sun. The CTOF data are reduced to ion fluxes and these are analyzed in conjunction with the results from model calculations of the pickup ion distributions in which not only, as usual, the interstellar neutral gas seed population has been accounted for, but also a component of heliospheric origin has been postulated, in order to explain the flux spectra in the mass interval 20-30 amu. The comparison of experiment and observations may be used also as a test of the recently emerging new understanding of the processes leading to the neutral particle ionization and consecutive coupling to the solar wind.

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Last Update: November 14, 1997, Peter Wurz